This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The control of the timing of placental separation from the uterine myometrium after fetal delivery is important for successful human parturition. However, there is little information on how this occurs. We suggest a "ripening process" within this tissue, akin to the processes in the cervix, myometrium and fetal membranes. In placenta accreta there is abnormal adherence of the placenta to the uterine wall, such that it fails to detach after fetal delivery. This is characterized by a lack of a normal placental basal plate at the site of placental attachment to the uterus. The insulin-like peptides: insulin-like peptide 4 (INSL4) and relaxin are produced by the invading trophoblast and decidual cells of the placental basal plate respectively. INSL4 has marked invasive properties and relaxin is a well characterized collagenolytic hormone. We propose here that INSL4 from the trophoblast causes excessive invasion into the myometrium when unprotected by a basal plate, whereas relaxin from the decidua of the basal plate is a collagenolytic signal for normal term placental separation. Therefore, in this pilot project, we will first determine (specific aim 1) the levels of INSL4 and relaxin gene and protein expression and show their cellular origins in trophoblast and basal plate at different stages of normal gestation. In specific aim 2, their expression will be compared in pathological specimens of placenta accreta, in areas of normal and abnormal placental attachment in the same tissue, as well as in the normal tissues from specific aim 1. In specific aim 3, primary villous trophoblast from areas of accreta and decidual cells from the normal areas of basal plate of the same patients, will be isolated and treated with a range of doses of INSL4 or relaxin. The secretion, by these cells, of different matrix metalloproteinases (MMPs), both collagenases and gelatinases, will be compared in response to INSL4 and relaxin. We anticipate publishing these data in peer-reviewed journals and developing the hypotheses further into applications for future research funding.